Zooplankton life cycles: Direct documentation of pelagic births and deaths relative to diapausing egg production
Zooplankton life cycles: Direct documentation of pelagic births and deaths relative to diapausing egg production
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浮游动物生命周期：直接记录与滞育产卵相关的中上层出生和死亡
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
B. Swan
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文献类型：
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作者：
S. T. Jarnagin;W. Kerfoot;B. Swan
浮游动物的人口统计数据在多个时间尺度上运作，对应于远洋单性生殖世代，越冬阶段和“卵子银行”。浮游生物的出生率和死亡率与季节性滞育产卵量的比较提供了对当地物种持久性的深入了解。多刺的枝藻（Bythotrephes）具有形态适应（刺和厚壁滞育卵），减少，但不消除，鱼类的捕食作用。由于尾刺保留在整个生命和消化的鱼内脏，沉积物陷阱中的脊椎积累直接文件的季节性死亡模式。在这里，我们对比沉积的脊椎和滞育蛋在最近殖民化的内陆湖（湖）沉积在一个更大的源湖（密歇根湖）。在内陆湖的直接死亡率估计符合传统的间接估计蛋比技术。虽然刺对内陆湖泊中丰富的小鱼有效，但个体容易被一年中的晚季幼鱼和大鱼摄食。实验室实验证实，鱼类是造成脊柱断裂的原因，估计占季节性死亡率的62-71%。晚季捕食的影响减少，因为滞育卵存活肠道通道，但每年生产的滞育卵是低的湖。在密歇根湖，浮游生物的出生（死亡）与滞育卵的关系更为平衡，这可能是因为携带卵的成虫在中央更深的沃茨找到了更好的避难所。由于刺捕获围网和滞育卵生存肠道通道，使用诱饵鱼和活威尔斯促进Bythotrephes分散。
Zooplankton demographics operate over multiple time scales corresponding to pelagic parthenogenetic generations, an overwintering stage, and an “egg bank.” Comparisons of pelagic birth and death rates with seasonal diapausing egg production provide insights into local species persistence. The spiny cladoceran (Bythotrephes) possesses morphological adaptations (spines and thick‐walled diapausing eggs) that lessen, but do not eliminate, predation effects by fish. Because caudal spines are retained throughout life and are indigestible in fish guts, spine accumulation in sediment traps directly documents patterns of seasonal mortality. Here, we contrast deposition of spines and diapausing eggs in a recently colonized inland lake (Lake Michigamme) with deposition in a larger source lake (Lake Michigan). Direct mortality estimates at the inland lake correspond well with traditional indirect estimates from egg ratio techniques. Although spines are effective against abundant small fish in the inland lake, individuals are susceptible to ingestion by late‐season young of year and larger fish. Laboratory experiments confirm that fish are responsible for spine breakage in the water column, accounting for an estimated 62–71% of seasonal mortality. Effects of late‐season predation are lessened because diapausing eggs survive gut passage, yet yearly production of diapausing eggs is low in Lake Michigamme. A more balanced pelagic birth(death) to diapausing egg relationship exists in Lake Michigan, probably because egg‐carrying adults find better refuge in central, deeper waters. Since spines catch on seines and diapausing eggs survive gut passage, use of bait fish and live wells promotes Bythotrephes dispersal.